Metal-ion dependence of the active-site conformation of the translesion DNA polymerase Dpo4 from Sulfolobus solfataricus

Crystal structures of a binary Mg²⁺-form Dpo4-DNA complex with 1,N²-etheno-dG in the template strand as well as of ternary Mg²⁺-form Dpo4-DNA-dCTP/dGTP complexes with 8-oxoG in the template strand have been determined. Comparison of their conformations and active-site geometries with those of the corresponding Ca²⁺-form complexes revealed that the DNA and polymerase undergo subtle changes as a result of the catalytically more active Mg²⁺ occupying both the A and B sites.